methodname ref to overloaded operator

Here's a very small work item for an XSLT hacker with a little time to
kill. (He says wishfully.) I can't refer to an overloaded operator. If
put this in a boostbook xml file:

<methodname>proto::functional::as_env::operator()</methodname>

I get this error:

Cannot find method named 'proto::functional::as_env::operator'

Looks like punctuation is being stripped before the lookup happens.
Clearly, if the function name is "operator", stripping punctuation is
the wrong thing to do.

-- 
Eric Niebler
BoostPro Computing
http://www.boostpro.com